1. Field of the Invention
The present invention relates to a spindle motor, and more particularly, to a spindle motor in which a bearing clearance is filled with a lubricant.
2. Description of the Related Art
Generally, a small spindle motor used for a hard disk drive (HDD) includes a fluid dynamic bearing assembly. In this case, a bearing clearance formed between a shaft and a sleeve of the fluid dynamic bearing assembly is filled with a lubricant, such as oil, or the like. The shaft is rotatably supported by forming a fluid dynamic pressure while compressing oil filling the bearing clearance.
In addition, the bearing clearance is formed by a top surface of the sleeve and a bottom surface of a rotor case that rotates in connection with the shaft. Meanwhile, a bearing clearance formed by the top surface of the sleeve and the bottom surface of the rotor case is also filled with the lubricant.
Meanwhile, when an impact is transmitted from the outside, the lubricant may be leaked outwardly from the bearing clearance, i.e., the clearance in which an interface between the lubricant and air is formed.
As described above, when the lubricant leaked to the outside is scattered, the inside of the spindle motor is contaminated by the lubricant.
In addition, when the lubricant is leaked to the outside, the fluid dynamic pressure generated by the lubricant is reduced, such that the performance of the spindle motor may be degraded and the usefullifespan thereof may be shortened.